Surveyor&#39;s illuminated backsight



F. J. SKRASTIN, JR

SURVEYORS ILLUMINATED BACKSIGHT Filed Aug. 15. 1948 IN V EN TOR.

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Jan. 16, 1951 V UNITED Patented jan. 16, 1951 SURVEYORSILLUMINATED BACKSIGHT Frederick J. Skrastin, Jr., Butte, Mont. 7 Application August :13, 1948 Serial No. 44,032

or when surveying in unilluminated places like 4 Claims. (Cl. 240-64) mines, tunnels, and the like, the primary object of the invention being to provide a practical and efficient self-luminous backsight upon which the cross hairs of the transit telescope can be easily centered from different remote locations around the sides of the backsight, the backsight being adapted to be suspended at a known point in the area to be surveyed, so that surveyors can measure the angle between the backsight and the next station. i M I Another important object of the invention is to, provide a compact and serviceable device of the character indicated above which provides a white luminous background for the black'cross hairs of the telescope of thesurveyors transit, thereby affording easier centering of the cross hairs on the backsight' i g Another important object of the invention is the provision of a device of the above indicated I character having a luminous sight head of transparent plastic capable of internaltransmission of light supplied to the head from an electric bulb energized by dr batteries contained in the device, whereby visibility of the device is enhanced and whereby the sight marks within the head are made to stand out in contrast to the head. I Y i "j; Other important objects and advantageousfea tures of the invention will be apparent from the following description and accompanying drawings, wherein merely for present purposes of il lustration, a specific embodiment of the inven'e tion is set forth in detail.

In the drawing:

Figure 1 is a contracted transverse vertical section taken through the illustrated device.

Figure 2 is a side elevation of the upper part of the device, and

Figure 3 is a top plan view thereof.

Referring in detail to the drawings, the numeral 5 designates the elongated preferably brass tube constituting the body or casing of the illustrated device, the upper and lower ends being internally threaded, as indicated at 6 and 1, respectively. Into the lower end of the casing is threadupper; end of the screw H through an insulator of a plurality of dry cells 15, such as flashlight batteries, confined thereabove in the casing 5, and therebyclosethe bulb circuit of the device.

Positioned in the casing 5 above the uppermost dry cell I5 isaninsulated washer is: having a central hole I! through which the center terminal [8 of the uppermost dr cell is exposed. Resting upon the washer I6 is the cylindrical brass bulb holder and reflector I9 having a threaded axial bore 28, opening at its lower'end in a concave recess 2| and at its upper end in a polished 'or reflector-coated frusto-conical de pression 22 constituting the reflector for the bulb 23, which is threaded in the bore 20 with its base contact 24 engaged with the terminal it of the uppermost dry cell It. In this arrangement the ferrule 25 of the bulb is in contact with the brass casing 5 with the bulb base contact 24 in contact" with the dry cell terminal it, so that contacting of the screw ll with the case of the lowermost dry cell I5 closes the circuit and illumines reflector I9, thereby holding this and the dry cell's E5 in place in the casing 5.

The sight head 2'! is formed with an axial conical depression 28in its upper end which terminates in a shallow cylindrical internally threaded portion 29 into which is threaded a flat plug 30 to a positionlflush withthe upper end ofthe head. A brass stud- 3|, threaded axially in the plug 30, has a key-hole opening 32 in its upper end to accommodate by sidewise insertion therein-the lowermost bead 33 of a flexible bead chain'3'4, the bead 33 beingretained'in the opening 32 by a removable brass cap 35 on the stud 3|. The uppermost bead. 36'. of the chain 34 is similarly associated with a stud 3'? having a key-hole 38 accommodating this bead, and a removable retaining cap 39, the upper end of the stud '3'! being transversely apertured at 4D to accommodate a slip ring 4| by which the device, is suspended for use from a suitable overhead support (not shown).

The sight. head 21 is made of transparent plastlc able to :transmit and reflect light internally which is impinged on its lower end from the bulb 23 and the reflector 22, various materials, such as acrylic and methacrylic plastics, being suitable. The walls of the conical depression 28 are disposed at an angle of to the axis of the head so as to reflect outwardly through the sides of the head light rays transmitted upwardly therein from the bulb 23 and thereby increase the luminosity of the head 21 and increase the illumination and visibility of the upper andlower sight marks 42 and 43 respectively, which are arranged axially in the head 21 in line with the center of the depression 28 and the chain 34. The plug 30 is of the same material as the head 21.

The upper sight mark 42 is axially aligned with but longer in diameter than the lower sight mark 43. These sight marks being of substantially the same length, with the upper end of the upper mark at the apex of the depression 28, and

the lower end of the lower mark at the upper end of the casing 5. The sight marks are constituted by bores formed in the head 21 in which light from the bulb 23 and reflected and transmitted Y when said bulb is energized, battery means within said casing below said reflector, a cap on the lower end of said casing retaining said battery means in said casing, switch means having an within the head 21 concentrates to provide highly illuminated marks contrasting by their brilliance with the relatively faint luminosity of the r.e

.It is this brilliant streak which the surveyor is Y able to see at long distances from the backsight It appears as a light blurr when not in .focus. I until properly focussed by the surveyor when it appears :as a thin streak of brilliance.

The .sight works 42, 43 are drilled out and are highly scratched to produce a contrast reflect with the head .21. I formed with a fine thread to produce a contrast with the luminous head 21.

What :is .claimed is:

l. A luminous surveyors backsight comprising a cylindrical translucent head having :anupper end and a lower end, a tubular casing secured to depend from said lower .end, illuminating means :said [ca-sing to direct light upwardly through the lower end of said head, an axial bore formed in said head providing a luminous sight .mark when illumined by said means, said upper :end of said head being formed with an Jaxialgrecess having internal screw threads at its upperzend, .a :zci-isk threaded into the upper end of said head, and suspending means secured .to saiddisk.

2. .A luminous surveyors backsight comprising a cylindrical translucent head having an upper end and a lower end, a tubular casing secured to, depend from said lower end, illuminatingmeans insaid casing to direct light upwardly through 1 the lower .end of :said head, an axial bore termed in said head providing :a luminous sight mark when illumined :by .said means, said upper :end of :said head :being formed with an recess internal screw threads at its upper end, a disk threaded into upper :endrof :said head; and suspending means secured to said di'skgsa id disk closing the upper :end of said recess, said recess being substantially larger in diameter than said bore and-inverted conical iormproviding a circular upwardly flaring wall acting in conjunct'ion with the underside of said .disk to reflect light from said bore and :light passing upwardly through said head .in downward and laterally outward directions.

3.. A luminous surveyorfs .backsight comprising :a luminous head formed of transparent material capable of internal transmission and reflection of light rays impinged upon one end thereof, axially extending means in :said head arranged The sight work 42 may be operating member on said cap for connecting said "bulb in circuit with said battery means to energize said bulb, and means connected to the upper end of said head'in axial alignment with said sight markmeans for suspending said backsight from an overhead support, the upper end of said head being formed with an axial conical depression actingas a reflector to reflect laterally outwardly within said head light rays transmitted upwardly through said .head from said bulb for intensifying the luminosity .of said sight means.

4. A luminous surveyors backsigh't comprising a luminous head formed of transparent material capable of internal transmission and reflection of light rays impinged upon one end thereof, axially extending means in said head arranged to be illuminated to greater brilliance than the eremainder of said head by light rays impinged thereon to provide sight mark means, .a tubular casing secured to depend from the lower end of said head, a bulb reflector in said casing immediatelybelow and facing the lowerendofsald head, an electric bulb mounted in said reflector where-' by light rays from said bulband .from said reflector are impinged upon .the lower .end .of said head when said bulb is energized, battery means within said casing .below said reflector, a cap on the lower end of said casing retaining said .bate ter-y means in said casing, switch .means having an operatingmember on said cap .ior connecting said bulb .in circuit with :said battery means to energize said bulb, .and means connected .to the upper end of said head in axial alignment with said sightmarkmeans .for suspending said backsight .from an overhead support, the upper. end of said head being formed with an axial conical depression acting .asa reflector to reflect laterally outwardly within said head light rays transmitted upwardly through said. head .from said bulb for intensifying the luminosity of said .sightmark means, a transparent plug closing the upper end of said conical depression, said suspending means being supportably connected with said plug ior suspending the backsight. 2

FREDERICK SIGt'ASTIN, JR.

- file of this patent:

' UNITED STATES PATENTS Number Name .f-Date 1,113,519 Wallace :Oc't. as, 1 914 1,875,048 Levene Aug. '30, 19.32 2,245,349 Lombardi June 10,, 1941 2,311,439 Iwanowicz Feb. 16,1943

, ,FQREIGN PATENTS Number Country Date 7 547,411 France Sept; 26, 

